February 2009
ISA Certified Control Systems Technician (CCST) program
Certified Control System Technicians (CCSTs) calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables.
This question comes from the Level I study guide, Domain 3, Troubleshooting. Level I represents a professional who has a five-year total of education, training, and/or experience.
CCST question
A process variable, which is to be maintained at some desired value (temperature, pressure, level, flow) by means of manipulating another process variable, is the:
A. Manipulated variable
B. Measured variable
C. Controlled variable
D. Disturbance variable
CCST answer
The correct answer is C, controlled variable.
The controlled variable by definition is the variable that the control system attempts to keep at a “set point” value. The set point may be constant or it may change. Typically, this part of the process is flow, level, temperature, pressure, or the like.
Nicholas Sheble (nsheble@isa.org) writes and edits Certification Review.
Read questions answered by our experts or join the email list.
